The fix for this issue is available in the latest InDesign release 16.2.1
Please update to this latest version of InDesign to get the fix.
Adobe InDesign team
An error occurred while saving the commentErin commented
I'm also running into this issue. The problems first started when I had 5 files open and shared for review (with edits added) and I needed to update my share links. I'd save File 2/5, have it open and active in my window, but when I went to update the share link, it would only show the share link for the previous file (File 1/5). This happened almost every time I restarted the software.
Now the whole program crashes when I try to share for review and I'm also getting the black File Share toolbox as the OC mentioned. My software is also completely updated.